#1 Gareth Bale - Real Madrid
Gareth Bale has been linked with moves to Manchester United several times in the past, however, nothing has ever materialised. Obviously, we wouldn't be coming towards a transfer window if Bale hasn't been mentioned in the same sentence as United.
In all seriousness, United probably need Bale more than ever right now. And should Real Madrid's dreadful form continue, then some of their players could look to move elsewhere or even some players could be allowed by the club to move elsewhere.
Gareth Bale is familiar with the English setting, as he made his rise through the Premier League. He is an English speaking person, so there's no need for any integration on the language front, either.
One thing which will make this deal hard for United to pull off is Bale's past with Spurs. He may feel like he owes it to the Spurs fans to keep his loyalty intact, by not playing for another Premier League side. Still, it won't force Mourinho into not making a move.
Bale is known for his electrifying speed, being one of the fastest players in Europe. There's no denying that if United are to sign him, then he would easily improve the side, and he would be a vast upgrade on Martial.
However, considering the current form of United, it would be interesting to see if Gareth Bale would want to move to Old Trafford. Anyway, this move, if it happens could do wonders to the club but its a bit farfetched to say the least.